如何在keras回调中调用model.evaluate()？

from keras.callbacks import Callback

class EvaluateCallback(Callback):
    def __init__(self, test_data):
        self.test_data = test_data

    def on_epoch_end(self, epoch, logs=None):
        x_test, y_test = self.test_data
        results = self.model.evaluate(x_test, y_test, batch_size=32)
        # 在这里可以对评估结果进行处理
        print("Test loss:", results[0])
        print("Test accuracy:", results[1])

# 创建模型和数据集
model = ...
x_test, y_test = ...

# 创建回调实例
evaluate_callback = EvaluateCallback(test_data=(x_test, y_test))

# 编译模型并开始训练
model.compile(...)
model.fit(..., callbacks=[evaluate_callback])